util-linux/mdev.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  *
   4  * mdev - Mini udev for busybox
   5  *
   6  * Copyright 2005 Rob Landley <rob@landley.net>
   7  * Copyright 2005 Frank Sorenson <frank@tuxrocks.com>
   8  *
   9  * Licensed under GPL version 2, see file LICENSE in this tarball for details.
  10  */
  11
  12 #include "libbb.h"
  13 #include "xregex.h"
  14
  15 struct globals {
  16         int root_major, root_minor;
  17 };
  18 #define G (*(struct globals*)&bb_common_bufsiz1)
  19 #define root_major (G.root_major)
  20 #define root_minor (G.root_minor)
  21
  22 /* Prevent infinite loops in /sys symlinks */
  23 #define MAX_SYSFS_DEPTH 3
  24
  25 /* We use additional 64+ bytes in make_device() */
  26 #define SCRATCH_SIZE 80
  27
  28 #if ENABLE_FEATURE_MDEV_RENAME
  29 /* Builds an alias path.
  30  * This function potentionally reallocates the alias parameter.
  31  */
  32 static char *build_alias(char *alias, const char *device_name)
  33 {
  34         char *dest;
  35
  36         /* ">bar/": rename to bar/device_name */
  37         /* ">bar[/]baz": rename to bar[/]baz */
  38         dest = strrchr(alias, '/');
  39         if (dest) { /* ">bar/[baz]" ? */
  40                 *dest = '\0'; /* mkdir bar */
  41                 bb_make_directory(alias, 0755, FILEUTILS_RECUR);
  42                 *dest = '/';
  43                 if (dest[1] == '\0') { /* ">bar/" => ">bar/device_name" */
  44                         dest = alias;
  45                         alias = concat_path_file(alias, device_name);
  46                         free(dest);
  47                 }
  48         }
  49
  50         return alias;
  51 }
  52 #endif
  53
  54 /* mknod in /dev based on a path like "/sys/block/hda/hda1" */
  55 /* NB: "mdev -s" may call us many times, do not leak memory/fds! */
  56 static void make_device(char *path, int delete)
  57 {
  58         const char *device_name;
  59         int major, minor, type, len;
  60         int mode = 0660;
  61 #if ENABLE_FEATURE_MDEV_CONF
  62         struct bb_uidgid_t ugid = { 0, 0 };
  63         parser_t *parser;
  64         char *tokens[5];
  65 #endif
  66 #if ENABLE_FEATURE_MDEV_EXEC
  67         char *command = NULL;
  68 #endif
  69 #if ENABLE_FEATURE_MDEV_RENAME
  70         char *alias = NULL;
  71         char aliaslink = aliaslink; /* for compiler */
  72 #endif
  73         char *dev_maj_min = path + strlen(path);
  74
  75         /* Force the configuration file settings exactly. */
  76         umask(0);
  77
  78         /* Try to read major/minor string.  Note that the kernel puts \n after
  79          * the data, so we don't need to worry about null terminating the string
  80          * because sscanf() will stop at the first nondigit, which \n is.
  81          * We also depend on path having writeable space after it.
  82          */
  83         major = -1;
  84         if (!delete) {
  85                 strcpy(dev_maj_min, "/dev");
  86                 len = open_read_close(path, dev_maj_min + 1, 64);
  87                 *dev_maj_min++ = '\0';
  88                 if (len < 1) {
  89                         if (!ENABLE_FEATURE_MDEV_EXEC)
  90                                 return;
  91                         /* no "dev" file, so just try to run script */
  92                         *dev_maj_min = '\0';
  93                 } else if (sscanf(dev_maj_min, "%u:%u", &major, &minor) != 2) {
  94                         major = -1;
  95                 }
  96         }
  97
  98         /* Determine device name, type, major and minor */
  99         device_name = bb_basename(path);
 100         /* http://kernel.org/doc/pending/hotplug.txt says that only
 101          * "/sys/block/..." is for block devices. "/sys/bus" etc is not.
 102          * But since 2.6.25 block devices are also in /sys/class/block.
 103          * We use strstr("/block/") to forestall future surprises. */
 104         type = S_IFCHR;
 105         if (strstr(path, "/block/"))
 106                 type = S_IFBLK;
 107
 108 #if ENABLE_FEATURE_MDEV_CONF
 109         parser = config_open2("/etc/mdev.conf", fopen_for_read);
 110
 111         /* If we have config file, look up user settings */
 112         while (config_read(parser, tokens, 4, 3, "# \t", PARSE_NORMAL)) {
 113                 regmatch_t off[1 + 9*ENABLE_FEATURE_MDEV_RENAME_REGEXP];
 114                 char *val;
 115
 116                 /* Fields: regex uid:gid mode [alias] [cmd] */
 117
 118                 /* 1st field: @<numeric maj,min>... */
 119                 if (tokens[0][0] == '@') {
 120                         /* @major,minor[-last] */
 121                         /* (useful when name is ambiguous:
 122                          * "/sys/class/usb/lp0" and
 123                          * "/sys/class/printer/lp0") */
 124                         int cmaj, cmin0, cmin1, sc;
 125                         if (major < 0)
 126                                 continue; /* no dev, no match */
 127                         sc = sscanf(tokens[0], "@%u,%u-%u", &cmaj, &cmin0, &cmin1);
 128                         if (sc < 1 || major != cmaj
 129                          || (sc == 2 && minor != cmin0)
 130                          || (sc == 3 && (minor < cmin0 || minor > cmin1))
 131                         ) {
 132                                 continue; /* no match */
 133                         }
 134                 } else { /* ... or regex to match device name */
 135                         regex_t match;
 136                         int result;
 137
 138                         /* Is this it? */
 139                         xregcomp(&match, tokens[0], REG_EXTENDED);
 140                         result = regexec(&match, device_name, ARRAY_SIZE(off), off, 0);
 141                         regfree(&match);
 142
 143                         //bb_error_msg("matches:");
 144                         //for (int i = 0; i < ARRAY_SIZE(off); i++) {
 145                         //      if (off[i].rm_so < 0) continue;
 146                         //      bb_error_msg("match %d: '%.*s'\n", i,
 147                         //              (int)(off[i].rm_eo - off[i].rm_so),
 148                         //              device_name + off[i].rm_so);
 149                         //}
 150
 151                         /* If not this device, skip rest of line */
 152                         /* (regexec returns whole pattern as "range" 0) */
 153                         if (result || off[0].rm_so
 154                          || ((int)off[0].rm_eo != (int)strlen(device_name))
 155                         ) {
 156                                 continue;
 157                         }
 158                 }
 159
 160                 /* This line matches: stop parsing the file
 161                  * after parsing the rest of fields */
 162
 163                 /* 2nd field: uid:gid - device ownership */
 164                 parse_chown_usergroup_or_die(&ugid, tokens[1]);
 165
 166                 /* 3rd field: mode - device permissions */
 167                 mode = strtoul(tokens[2], NULL, 8);
 168
 169                 val = tokens[3];
 170                 /* 4th field (opt): >alias */
 171 #if ENABLE_FEATURE_MDEV_RENAME
 172                 if (!val)
 173                         break;
 174                 aliaslink = *val;
 175                 if (aliaslink == '>' || aliaslink == '=') {
 176                         char *s;
 177 #if ENABLE_FEATURE_MDEV_RENAME_REGEXP
 178                         char *p;
 179                         unsigned i, n;
 180 #endif
 181                         char *a = val;
 182                         s = strchrnul(val, ' ');
 183                         val = (s[0] && s[1]) ? s+1 : NULL;
 184                         s[0] = '\0';
 185 #if ENABLE_FEATURE_MDEV_RENAME_REGEXP
 186                         /* substitute %1..9 with off[1..9], if any */
 187                         n = 0;
 188                         s = a;
 189                         while (*s)
 190                                 if (*s++ == '%')
 191                                         n++;
 192
 193                         p = alias = xzalloc(strlen(a) + n * strlen(device_name));
 194                         s = a + 1;
 195                         while (*s) {
 196                                 *p = *s;
 197                                 if ('%' == *s) {
 198                                         i = (s[1] - '0');
 199                                         if (i <= 9 && off[i].rm_so >= 0) {
 200                                                 n = off[i].rm_eo - off[i].rm_so;
 201                                                 strncpy(p, device_name + off[i].rm_so, n);
 202                                                 p += n - 1;
 203                                                 s++;
 204                                         }
 205                                 }
 206                                 p++;
 207                                 s++;
 208                         }
 209 #else
 210                         alias = xstrdup(a + 1);
 211 #endif
 212                 }
 213 #endif /* ENABLE_FEATURE_MDEV_RENAME */
 214
 215 #if ENABLE_FEATURE_MDEV_EXEC
 216                 /* The rest (opt): command to run */
 217                 if (!val)
 218                         break;
 219                 {
 220                         const char *s = "@$*";
 221                         const char *s2 = strchr(s, *val);
 222
 223                         if (!s2)
 224                                 bb_error_msg_and_die("bad line %u", parser->lineno);
 225
 226                         /* Correlate the position in the "@$*" with the delete
 227                          * step so that we get the proper behavior:
 228                          * @cmd: run on create
 229                          * $cmd: run on delete
 230                          * *cmd: run on both
 231                          */
 232                         if ((s2 - s + 1) /*1/2/3*/ & /*1/2*/ (1 + delete)) {
 233                                 command = xstrdup(val + 1);
 234                         }
 235                 }
 236 #endif
 237                 /* end of field parsing */
 238                 break; /* we found matching line, stop */
 239         } /* end of "while line is read from /etc/mdev.conf" */
 240
 241         config_close(parser);
 242 #endif /* ENABLE_FEATURE_MDEV_CONF */
 243
 244         if (!delete && major >= 0) {
 245
 246                 if (ENABLE_FEATURE_MDEV_RENAME)
 247                         unlink(device_name);
 248
 249                 if (mknod(device_name, mode | type, makedev(major, minor)) && errno != EEXIST)
 250                         bb_perror_msg_and_die("mknod %s", device_name);
 251
 252                 if (major == root_major && minor == root_minor)
 253                         symlink(device_name, "root");
 254
 255 #if ENABLE_FEATURE_MDEV_CONF
 256                 chown(device_name, ugid.uid, ugid.gid);
 257
 258 #if ENABLE_FEATURE_MDEV_RENAME
 259                 if (alias) {
 260                         alias = build_alias(alias, device_name);
 261
 262                         /* move the device, and optionally
 263                          * make a symlink to moved device node */
 264                         if (rename(device_name, alias) == 0 && aliaslink == '>')
 265                                 symlink(alias, device_name);
 266
 267                         free(alias);
 268                 }
 269 #endif
 270 #endif
 271         }
 272
 273 #if ENABLE_FEATURE_MDEV_EXEC
 274         if (command) {
 275                 /* setenv will leak memory, use putenv/unsetenv/free */
 276                 char *s = xasprintf("MDEV=%s", device_name);
 277                 putenv(s);
 278                 if (system(command) == -1)
 279                         bb_perror_msg_and_die("can't run '%s'", command);
 280                 unsetenv("MDEV");
 281                 free(s);
 282                 free(command);
 283         }
 284 #endif
 285
 286         if (delete) {
 287                 unlink(device_name);
 288                 /* At creation time, device might have been moved
 289                  * and a symlink might have been created. Undo that. */
 290 #if ENABLE_FEATURE_MDEV_RENAME
 291                 if (alias) {
 292                         alias = build_alias(alias, device_name);
 293                         unlink(alias);
 294                         free(alias);
 295                 }
 296 #endif
 297         }
 298 }
 299
 300 /* File callback for /sys/ traversal */
 301 static int FAST_FUNC fileAction(const char *fileName,
 302                 struct stat *statbuf UNUSED_PARAM,
 303                 void *userData,
 304                 int depth UNUSED_PARAM)
 305 {
 306         size_t len = strlen(fileName) - 4; /* can't underflow */
 307         char *scratch = userData;
 308
 309         /* len check is for paranoid reasons */
 310         if (strcmp(fileName + len, "/dev") != 0 || len >= PATH_MAX)
 311                 return FALSE;
 312
 313         strcpy(scratch, fileName);
 314         scratch[len] = '\0';
 315         make_device(scratch, 0);
 316
 317         return TRUE;
 318 }
 319
 320 /* Directory callback for /sys/ traversal */
 321 static int FAST_FUNC dirAction(const char *fileName UNUSED_PARAM,
 322                 struct stat *statbuf UNUSED_PARAM,
 323                 void *userData UNUSED_PARAM,
 324                 int depth)
 325 {
 326         return (depth >= MAX_SYSFS_DEPTH ? SKIP : TRUE);
 327 }
 328
 329 /* For the full gory details, see linux/Documentation/firmware_class/README
 330  *
 331  * Firmware loading works like this:
 332  * - kernel sets FIRMWARE env var
 333  * - userspace checks /lib/firmware/$FIRMWARE
 334  * - userspace waits for /sys/$DEVPATH/loading to appear
 335  * - userspace writes "1" to /sys/$DEVPATH/loading
 336  * - userspace copies /lib/firmware/$FIRMWARE into /sys/$DEVPATH/data
 337  * - userspace writes "0" (worked) or "-1" (failed) to /sys/$DEVPATH/loading
 338  * - kernel loads firmware into device
 339  */
 340 static void load_firmware(const char *const firmware, const char *const sysfs_path)
 341 {
 342         int cnt;
 343         int firmware_fd, loading_fd, data_fd;
 344
 345         /* check for /lib/firmware/$FIRMWARE */
 346         xchdir("/lib/firmware");
 347         firmware_fd = xopen(firmware, O_RDONLY);
 348
 349         /* in case we goto out ... */
 350         data_fd = -1;
 351
 352         /* check for /sys/$DEVPATH/loading ... give 30 seconds to appear */
 353         xchdir(sysfs_path);
 354         for (cnt = 0; cnt < 30; ++cnt) {
 355                 loading_fd = open("loading", O_WRONLY);
 356                 if (loading_fd != -1)
 357                         goto loading;
 358                 sleep(1);
 359         }
 360         goto out;
 361
 362  loading:
 363         /* tell kernel we're loading by `echo 1 > /sys/$DEVPATH/loading` */
 364         if (full_write(loading_fd, "1", 1) != 1)
 365                 goto out;
 366
 367         /* load firmware by `cat /lib/firmware/$FIRMWARE > /sys/$DEVPATH/data */
 368         data_fd = open("data", O_WRONLY);
 369         if (data_fd == -1)
 370                 goto out;
 371         cnt = bb_copyfd_eof(firmware_fd, data_fd);
 372
 373         /* tell kernel result by `echo [0|-1] > /sys/$DEVPATH/loading` */
 374         if (cnt > 0)
 375                 full_write(loading_fd, "0", 1);
 376         else
 377                 full_write(loading_fd, "-1", 2);
 378
 379  out:
 380         if (ENABLE_FEATURE_CLEAN_UP) {
 381                 close(firmware_fd);
 382                 close(loading_fd);
 383                 close(data_fd);
 384         }
 385 }
 386
 387 int mdev_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 388 int mdev_main(int argc UNUSED_PARAM, char **argv)
 389 {
 390         RESERVE_CONFIG_BUFFER(temp, PATH_MAX + SCRATCH_SIZE);
 391
 392         /* We can be called as hotplug helper */
 393         /* Kernel cannot provide suitable stdio fds for us, do it ourself */
 394 #if 1
 395         bb_sanitize_stdio();
 396 #else
 397         /* Debug code */
 398         /* Replace LOGFILE by other file or device name if you need */
 399 #define LOGFILE "/dev/console"
 400         /* Just making sure fd 0 is not closed,
 401          * we don't really intend to read from it */
 402         xmove_fd(xopen("/", O_RDONLY), STDIN_FILENO);
 403         xmove_fd(xopen(LOGFILE, O_WRONLY|O_APPEND), STDOUT_FILENO);
 404         xmove_fd(xopen(LOGFILE, O_WRONLY|O_APPEND), STDERR_FILENO);
 405 #endif
 406
 407         xchdir("/dev");
 408
 409         if (argv[1] && !strcmp(argv[1], "-s")) {
 410                 /* Scan:
 411                  * mdev -s
 412                  */
 413                 struct stat st;
 414
 415                 xstat("/", &st);
 416                 root_major = major(st.st_dev);
 417                 root_minor = minor(st.st_dev);
 418
 419                 /* ACTION_FOLLOWLINKS is needed since in newer kernels
 420                  * /sys/block/loop* (for example) are symlinks to dirs,
 421                  * not real directories.
 422                  * (kernel's CONFIG_SYSFS_DEPRECATED makes them real dirs,
 423                  * but we can't enforce that on users)
 424                  */
 425                 if (access("/sys/class/block", F_OK) != 0) {
 426                         /* Scan obsolete /sys/block only if /sys/class/block
 427                          * doesn't exist. Otherwise we'll have dupes.
 428                          */
 429                         recursive_action("/sys/block",
 430                                 ACTION_RECURSE | ACTION_FOLLOWLINKS,
 431                                 // not needed now? | ACTION_QUIET
 432                                 fileAction, dirAction, temp, 0);
 433                 }
 434                 recursive_action("/sys/class",
 435                         ACTION_RECURSE | ACTION_FOLLOWLINKS,
 436                         fileAction, dirAction, temp, 0);
 437         } else {
 438                 char *seq;
 439                 char *action;
 440                 char *env_path;
 441                 char seqbuf[sizeof(int)*3 + 2];
 442                 int seqlen = seqlen; /* for compiler */
 443
 444                 /* Hotplug:
 445                  * env ACTION=... DEVPATH=... [SEQNUM=...] mdev
 446                  * ACTION can be "add" or "remove"
 447                  * DEVPATH is like "/block/sda" or "/class/input/mice"
 448                  */
 449                 action = getenv("ACTION");
 450                 env_path = getenv("DEVPATH");
 451                 if (!action || !env_path)
 452                         bb_show_usage();
 453
 454                 seq = getenv("SEQNUM");
 455                 if (seq) {
 456                         int timeout = 2000 / 32;
 457                         do {
 458                                 seqlen = open_read_close("mdev.seq", seqbuf, sizeof(seqbuf-1));
 459                                 if (seqlen < 0)
 460                                         break;
 461                                 seqbuf[seqlen] = '\0';
 462                                 if (seqbuf[0] == '\n' /* seed file? */
 463                                  || strcmp(seq, seqbuf) == 0 /* correct idx? */
 464                                 ) {
 465                                         break;
 466                                 }
 467                                 usleep(32*1000);
 468                         } while (--timeout);
 469                 }
 470
 471                 snprintf(temp, PATH_MAX, "/sys%s", env_path);
 472                 if (!strcmp(action, "remove"))
 473                         make_device(temp, 1);
 474                 else if (!strcmp(action, "add")) {
 475                         make_device(temp, 0);
 476
 477                         if (ENABLE_FEATURE_MDEV_LOAD_FIRMWARE) {
 478                                 char *fw = getenv("FIRMWARE");
 479                                 if (fw)
 480                                         load_firmware(fw, temp);
 481                         }
 482                 }
 483
 484                 if (seq && seqlen >= 0) {
 485                         xopen_xwrite_close("mdev.seq", utoa(xatou(seq) + 1));
 486                 }
 487         }
 488
 489         if (ENABLE_FEATURE_CLEAN_UP)
 490                 RELEASE_CONFIG_BUFFER(temp);
 491
 492         return 0;
 493 }